Work in our laboratory demonstrated that the Walker 256 ascites tumor cell produces large quantities of free fatty acids (FFA) when incubated in vitro. This FFA production is apparently due to active lipolytic enzymes. Both an acidic and neutral-alkaline pH optimum lipolytic activity have been recognized with these cells. Ascites tumor cells and perhaps other types of tumors seem to place great demand upon fatty acids as a source of metabolic energy and for growth. In view of these considerations and that this area of tumor lipid metabolism is incompletely understood, we propose to examine the lipolytic activities of the Walker tumor in greater detail. The substrate specificities and subcellular distribution of the lipolytic enzymes will be determined. Preliminary experiments suggest that this tumor might release lipase enzymes or other lipolytic factors which could influence lipolysis in normal cells. It is known that depletion of body fat occurs in cancer bearing patients. The ability of the ascites tumor to influence lipolysis in adipose tissue of normal and tumor bearing rats will be evaluated.